﻿Shader "Shader/Disappear"
{
	Properties
	{
		_MainTex("Texture", 2D) = "white" {}
		_DisappearOffset("Disappear Offset",Range(-0.5,0.5)) = -0.5
	}
		SubShader
		{
			Tags { "RenderType" = "Opaque" }


			Pass
			{
				CGPROGRAM
				#pragma vertex vert
				#pragma fragment frag

				#include "UnityCG.cginc"

				struct appdata
				{
					float4 vertex : POSITION;
					float2 uv : TEXCOORD0;
				};

				struct v2f
				{
					float3 uv : TEXCOORD0;
					float4 vertex : SV_POSITION;
				};

				sampler2D _MainTex;
				float4 _MainTex_ST;
				uniform float _DisappearOffset;

				v2f vert(appdata v)
				{
					v2f o;
					o.vertex = UnityObjectToClipPos(v.vertex);
					//输出的uv中xy存储uv值,z存储用于Clip的参数值
					o.uv.xy = TRANSFORM_TEX(v.uv, _MainTex);
					//因为模型空间中y值范围为(-0.5,0.5)，所以还需要进行偏移以保证裁剪的正确
					o.uv.z = _DisappearOffset - v.vertex.y;
					return o;
				}

				fixed4 frag(v2f i) : SV_Target
				{
					clip(i.uv.z);
				// sample the texture
				fixed4 col = tex2D(_MainTex, i.uv.xy);
				return col;
			}
			ENDCG
		}
		}
}